"Total credit market debt in the United States was $52.6 trillion at the end of the third quarter, including $2 trillion owed by foreigners. In the past decade, debt has grown at an annual rate of 7.8%, while nominal GDP has grown at an annual rate of 4.3%. Over the same period, household, government and financial debt have grown at annual rates of 7.9%, 7.3% and 8.1%, respectively. It is unlikely that debt will be able to grow faster than nominal GDP in perpetuity. The ratio of overall debt to GDP currently stands at 369%, which is the highest ratio on record. The ratio of debt to GDP has been continually increasing since the early 1950s. In the past decade, overall debt outstanding has increased by $27.2 trillion, while nominal GDP has increased by $4.9 trillion."

"The United States of America preliminary prospectus dated March 5, 2010", Grant's Interest Rate Observer

"First, the relationship between government debt and real GDP growth is weak for debt/GDP ratios below a threshold of 90 percent of GDP. Above 90 percent, median growth rates fall by one percent, and average growth falls considerably more."

Carmen M. Reinhart and Kenneth S. Rogoff, "Growth in a Time of Debt", NBER Working Series Paper, January 2010